Socket contact and method of manufacture



Oct. 15, 1968 A. J. VARRIN 3,406,376

SOCKET CONTACT AND METHOD OF MANUFACTURE l rani Filed Sept. 26, 1966 INVENTOP. HMORE a]; Mme/N United States atent 3,406,376 SOCKET CONTACT AND METHOD OF MANUFACTURE Andre J. Varrin, Long Beach, Calif., assignor to International Telephone and Telegraph Corporation, New York, N.Y., a corporation of Maryland Filed Sept. 26, 1966, Ser. No. 581,993 3 Claims. (Cl. 339-258) ABSTRACT OF THE DISCLOSURE A socket contact for receiving a terminal pin. The contact is formed from a thin body of spring conductive material which is cut to provide an elongated tongue which is bent nearly 180 so that its free end extends close to but spaced from the body surface. The body is rolled into a tubular shape with the tongue extending generally parallel to the axis of the body. The tongue serves as a spring to furnish resilient positive contact when the terminal pin is inserted in the body.

This invention relates to electrical connector contacts and terminals and more particularly to an improved female or socket contact and to a method for making such contact.

It is a primary object of this invention to provide a new and improved electrical connector socket contact which is inexpensive to manufacture and which provides excellent contact with a terminal pin inserted in the socket.

Another object of this invention is to provide such a socket contact formed of a one piece construction having a spring member integral therewith for insuring positive contact with a terminal pin.

Yet another object of this invention is to provide such a socket contact having three supporting surfaces to frictionally :and resiliently engage a terminal pin thereby obtaining three point conductivity.

Still another object of this invention is to provide a unique and simplified method for forming a socket contact that primarily involves merely stamping and rolling operations.

In accordance with one embodiment of this invention, a socket contact is simply formed from a thin body of spring conductive material which is cut to provide an elongated tongue having one end attached to the stamping and the other end free to be moved. The tongue is bent in a reverse direction slightly less than 180 so that its free end extends close to, but slightly spaced from the body surface. The body is then rolled into a tubular shape to form a socket contact with the tongue positioned within the body and extending nearly parallel to the axis of the tubular body. The free end of the tongue is located near the entry to the socket so that when a pin is in serted therein it frictionally engages the tongue forcing the tongue slightly radially outwardly thus providing good electrical contact. The tongue in effect serves as a cantilever type spring to furnish resilient positive contact that accommodates relatively wide tolerance variations in socket and pin dimensions.

To provide three point contact for a terminal inserted within the socket body, two elongated projections or flutes are stamped into the socket body when it is in its flat form. These flutes are angularly spaced with respect to the tongue and extend generally parallel to the tongue whereby the two flutes and the tongue engage a terminal pin inserted within the socket body. Such an arrangement performs admirably and is inexpensive.

For a more thorough understanding of the invention refer to the following detailed description and drawing in which:

FIG. 1 is a perspective view of the socket contact of the invention and a portion of a terminal to be inserted therein;

FIG. 2 is a partially sectionalized side elevational view of the socket contact with a terminal inserted therein;

FIG. 3 is a view on line 3-3 of FIG. 2;

FIG. 4 is a view of the socket body in flat form after a preliminary stamping operation; and

FIG. 5 is a view of FIG. 4 after the tongue has been bent.

Referring now to FIGS. 1 and 2, the socket contact of the inventon may be seen to include a generally tubular body 10 made of thin flexible or springlike conducting material, such as beryllium copper, having a forward end 10a for receiving a cylindrical contact terminal pin 11 and a rear end 10b shown [attached to a conductor wire or other conductive element 12. In accordance with the invention, an elongated tongue 14 is cut from the side wall of the body 10 thus creating a slot 16, and the tongue is bent forwardly slightly less than 180 to the position illustrated in FIGS. 1 and 2. As shown, the forward or free end 14a of the tongue is slightly spaced from the inner adjacent wall surface of body 10 while the rear end 1412 of the tongue is integral with body 10 at approximately the midpoint of the socket.

More precisely, a section 140 adjacent the rear end 14b of the tongue is bent a full 180 into engagement with the adjacent inner surface of the body 14, while the remaining portion is bent slightly less than 180 about the forward edge of section 140.

With such an arrangement, the tongue 14 functions as a cantilever type spring about the forward edge of section 14c due to the springiness of the metal. Note that the use of section 14c in engagement with body 14 causes the cantilever spring stresses to be primarily located in the area of the leading edge of section 14c. If section 14c were spaced from the body surface, the stress would be localized at the tongue rear end 14b which has already been stressed by the initial bending operation. The terminal pin 11 inserted into the socket body engages the free end of the tongue and forces the forward portion of the tongue slightly radially outwardly to thereby obtain good frictional and electrical contact.

To further provide good supporting surfaces for the terminal pin, there is provided a pair of elongated flutes 18 and 20 which are stamped into the body pin to pr0- ject inwardly. From the exterior of the socket body, these flutes appear as grooves, whereas on the interior surface of the body they appear as projections. The tongue 14 and the flutes 18 and 20 are angularly spaced, preferably equidistant, around the periphery of the socket body and extend axially in parallel relation.

Accordingly, when terminal pin 11 is inserted into the socket body it engages the forward ends of the flutes 18 and 20 and the tongue 14 and is frictionally gripped by these elements thereby obtaining good electrical 3 point conductivity as shown in FIG. 3. Note that the forward ends of the flutes and the tongue terminate at approximately the same distance from the forward end 10a of the socket body and that the forward ends are sloped or tapered outwardly so :as to smoothly receive the terminal pin 11. It will be appreciated that the flexibility of tongue 14 enables the socket body to receive terminal pins having a considerable tolerance variation and yet the tongue in cooperation with the flutes 18 and 20 will provide the necessary electrical and mechanical connection. Note also that the tongue 14 is circumferentially curved to conform to the shape of terminal pin 11 so that more than mere line contact is normally obtained between the pin and tongue.

In the preferred form of the invention, the forward end 14a of the tongue remains spaced from the adjacent inner wall of the socket after the terminal pin 11 is inserted, as shown in FIG. 2. With such an arrangement, the forces necessary to insert or extract terminal pin 11 are determined solely by the tongue characteristics and the pin. To enable the tongue forward end 14a to be flared outwardly and remain spaced from body when a pin is inserted while still minimizing the space required, the end 14a is coined or thinned at its outer tip, as seen in FIG. 2.

The existence of the flared forward end 14a also limits the outward movement of the tongue in the event an attempt is made to insert an over-sized pin. Thus, the tongue cannot be damaged by being moved more than a given amount and the cantilever spring forces of the tongue can be more accurately maintained. This feature can be quite significant when the socket is employed in critical application wherein the tolerance range of insertion and extraction forces is relatively narrow.

Although the socket of the invention may, of course,

be produced in a variety of sizes, it is most likely to be used in miniature components. To illustrate the precision necessary and which can be obtained with the invention, the dimensions used in a version of the socket scheduled for production will be given. For a socket made of material .009 thick and having an outer diameter of about .160", the entire tongue length is about .316 with the movable portion being about .250", while the tongue width is about .095". In its free state without a pin inserted in the socket, the radially outer edge of the tongue forward end 14a is spaced about .012 from the inner wall of the socket. When the mating pin is inserted, the tongue is urged outwardly so that the outer edge of the tongue forward end is spaced from the body wall about .003" so that the frictional forces are produced solely by the spring.

In addition to the foregoing functional and operational advantages of the socket contact of the invention, the contact is also low in cost and simple to manufacture. In accordance with the method of the invention, the socket contact is simply fabricated by stamping, bending, coining and rolling operations, without requiring any machining. As the first step the two flutes 18 and 20 may be stamped into the body of material and the tongue 14 may be cut from the material, as shown in FIG. 4. As the next step of the fabrication process, the coining of the tongue forward end 14a may be performed if desired. Next, the tongue 14 is bent beyond its elastic limit about its end 14b attached to the socket body through an angle slightly less than 180 to the position shown in FIGS. 1 and 2 wherein the forward or free end 14a of the tongue is spaced slightly from the inner wall of the socket body. The section 140 may be stamped in the tongue either during the initial stamping operation or after the tongue is being bent into position. The body illustrated is then simply rolled in a suitable manner into its tubular shape illustrated in FIGS. 1, 2, and 3 with the edges 10c and 10d of the body 10 forming an axially extending seam.

Although the socket is shown as a rectangular blank in the drawings, by way of illustration, the fabrication process may be conveniently performed while the contact material is in strip form so that a series of sockets may be made. Hence, the outer shape of the socket need not be out until just prior to the rolling operation and the sockets may remain partially interconnected until after rolling operation.

From the foregoing it will be appreciated that the socket body can be very inexpensively formed requiring merely a few Well-known manufacturing techniques and involving a minimum of close tolerance work. There is no machining required, and little operator skill involved. Also, since the spring is formed integral with the socket body, no assembly steps are needed.

The tapered forward surfaces of the flutes and of the tongue also insure that the terminal pin is guided accurately into the socket body so that the tongue is not damaged by the pin. Also, as explained, the outer cylindrical surface of the socket body naturally limits the outward movement of the tongue 14 so that the tongue cannot be over stressed if an oversized pin is inserted in the socket.

While only a single embodiment of the invention has been illustrated and described, it should be understood that various other modifications and changes will come to the mind of one skilled in the art in light of the foregoing disclosure. For example, the inward projections, or flutes 18 and 20 can be given shapes other than that illustrated, such as an interrupted series of projections rather than a continuous elongated projection. Also, while two flutes and one tongue represent the preferred approach for the socket body, it should be understood that a socket body may be formed with more tongues or with more or less flutes as desired. Accordingly, it is intended that all such modifications and variations that fall within the spirit and scope of the invention be included in the appended claims.

What is claimed is:

1. An electric connector socket contact for receiving a connector terminal pin comprising:

a generally longitudinally split tubular body formed from a flexible sheet of conducting material and having a forward end for receiving a terminal pin and a rear end to be connected to other conducting means; and

an elongated tongue having its rear end integral with said body at a point spaced from the forward and rear ends of said body, the outline of said tongue being cut from said sheet of material so as to provide an elongated slot in said body extending rearwardly of said point, said tongue being bent back upon said body at said point with said tongue extending forwardly within said body, said tongue having a forward end spaced radially inwardly from the inner wall of the body so that the tongue serves as a spring to provide good frictional contact with a terminal pin inserted within the body.

2. The socket contact of claim 1 including inwardly projecting longitudinally extending elements formed in the side wall of said body, said elements being angularly spaced from said tongue and in spaced parallel relation with each other and said tongue whereby said elements together with said tongue provide surfaces for frictionally engaging a terminal pin inserted within said body and to thus insure a plurality of good electrically conducting points with the pin.

3. The socket contact of claim 1 wherein said tongue is formed with a section at its rear end which engages an adjacent inner surface of said socket body so that said tongue pivots about the forward edge of said section as the forward end of the tongue is depressed when a pin is inserted therein.

References Cited UNITED STATES PATENTS 1,194,122 8/1916 Ball 339-258 2,206,662 7/ 1940 Conrad et al. 2,759,165 8/ 1956 Batcheller 339258 X 2,969,517 1/ 1961 Gluck 339-258 X FOREIGN PATENTS 944,875 11/1948 France. 996,979 9/ 1951 France.

MARVIN A. CHAMPION, Primary Examiner.

P. TEITELBAUM, Assistant Examiner. 

